NEW YORK — As Gov. Eliot Spitzer prepares to leave office, the disgraced politician faces a tangled battle with prosecutors that will send lawyers into murky legal territory.

A law enforcement official said that Spitzer’s high-powered defense team was thought to be negotiating a plea deal with prosecutors over his connection to a high-end prostitution ring, but attorneys were not commenting Thursday about the discussions.

The legal battle occurred as Lt. Gov. David Paterson prepared to take over the state following Spitzer’s fall from power. Paterson said he spoke to Spitzer on Thursday and “told him how sorry I was this happened.”

“I promised the governor yesterday that I would commit myself to the people of this great state, that we would have stability and continue in these challenges that lie ahead,” Paterson said Thursday. “Now we have to get New York back on track.”

Paterson takes over Monday, and he will become New York’s first black governor and the nation’s first legally blind chief executive.

Spitzer, a married father of three teenage girls, faces a much more dubious future after he was accused of spending tens of thousands of dollars on prostitutes — including a tryst with a 22-year-old call girl in Washington the night before Valentine’s Day. Officials said that Spitzer initially drew the attention of authorities with suspicious money transfers, which will be a key part of any possible criminal case.

Among the possible charges that could be brought against Spitzer: soliciting and paying for sex; violating the Mann Act, the 1910 federal law that makes it a crime to induce someone to cross state lines for immoral purposes; and illegally arranging cash transactions to conceal their purpose.

But legal experts said that bringing charges and getting a conviction would be unusual, considering federal authorities rarely charge the customers in illegal sex or drug cases. A likely outcome could be what is called a “deferred prosecution agreement,” which could leave Spitzer on probation with charges dropped if he did not get into any more trouble.

Gerald Lefcourt, past president of the National Association of Criminal Defense Attorneys, said criminal charges against Spitzer would be “stretching federal statutes to a place they’ve never been.”

Edward Little, who worked in the public corruption unit of the Manhattan federal prosecutor’s office for eight years in the 1980s, said it would be “piling on” to bring charges now.

“I think it would be outrageous if they went after him any further on this,” he said. “Solicitation cases are typically pled down to minor charges, and just because he was governor doesn’t mean he should be treated any more harshly unless they impacted his duties as governor.”

He added: “Even though I personally think it’s reprehensible, it doesn’t mean it’s criminal. He’s resigned, which is probably the ultimate penalty in this case, so we should let it be.”

The most likely charge Spitzer could face is structuring — breaking sums of money down into smaller amounts to hide the true purpose of the funds — but it is rarely brought as a stand-alone charge.

Lawyers said they are usually brought in money-laundering cases or as part of some larger criminal activity such as drug dealing.

Also, such cases usually involve hiding the source of the money. There is no reason to think that Spitzer, a millionaire many times over, used illegal funds to pay for anything.

A Mann Act violation may be another stretch.

The law is not typically applied to buying sex from adult women, even if, according to court papers, the client identified as Spitzer by law enforcement officials managed to break almost every part of the law by arranging for the woman’s train and hotel fares, right down to the mini-bar at the hotel.

Prosecutors could also face trouble if Spitzer was the only one of the 10 clients named in the affidavit to be charged.